[Edu-sig] Python teacher notes, preparing for class...

[kirby urner]

On Thu, Aug 30, 2018 at 3:02 AM Wes Turner <wes.turner at gmail.com> wrote:

> > By default, the sorted function looks at the leftmost element of a tuple
> or other iterable, when sorting...
>
>
You're right, my presentation is unclear.  I'll fix it.

The way it reads, it seems like you're implying that sorted() does this:
>
>
Yes, and that's wrong.

> >>> l = [(3, 2), (3, 1), (1, 1, 2), (1, 1)]
> >>> sorted(l, key=lambda x: x[0])
> [(1, 1, 2), (1, 1), (3, 2), (3, 1)]
>
>
> > You'll find some excellent overview of the magic methods in this essay
> by Rafe Kettler: A Guide to Python's Magic Methods. He's mostly looking at
> Python 2.7, so does not pick up on the __next__ method, however you'll be
> able to fill in the blanks thanks to this course
>
> This is unclear to me. What does the next() function do? How do I find the
> docs and source for it?
>
>
next(obj) triggers obj.__next__() which in 2.7 is named next internally
i.e. isn't magic.

__next__ is the main driver of iterators e.g. for loops hit __next__ over
and over as they loop over whatever.

True, a list (iterable) doesn't have a  __next__, but a for loop implicitly
applies __iter__ (called by the iter function) which turns iterables into
iterators.

> These are misspelled:
>
> > comparitor
> > compartor
>
>
Will fix next.



> These are great:
> - http://www.scipy-lectures.org/intro/language/python_language.html
> -
> http://nbviewer.jupyter.org/github/jrjohansson/scientific-python-lectures/blob/master/Lecture-1-Introduction-to-Python-Programming.ipynb
>   - Something about sorted with a link to the docs would be a good
> addition.
>
>
Thanks.  Yes, I'll add some links to the docs as you suggest.  Great
feedback!

Actually as part of my class I'm showing them edu-sig and other python.org
lists, so we were actually viewing this conversation.  I'll extend that to
showing your corrections, as I want to demonstrate how the Python community
all teaches each other, is friendly and so on.

Kirby
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